Curve for drawing ellipses



June 20, 1950 J. A. FULTON 2,512,492

CURVE FOR DRAWING ELLIPSES Filed April 21, 1945 2 Sheets-Sheet 1 INVENTOR JACK A. FULTON PE R ATTORNEY u 0 J. A. FULTON 2,512,492

CURVE FOR DRAWING ELLIPSES Filed April 21, 1945 2 Sheets-Sheet 2 Ea. 4 5 10 j/ INVENTOR JACK A. FULTON ATTORNEY Patented June 20, 1950 cunvnroa DRAWING ELLIPSES as; 11.31am, m 'fi ll fl i 21, 194s, 'seria versgam (c1. ace- 12 11 scams.

This invention relates to drawing implements 'and mreparticularly to drawing implements which are adapted to be employed ting approximate ellipses;

In the. making of drawings; orthographic, axonometric, or perspective, it is frequently necessary to rapidly construct ellipseswhich: are smooth in outline, free'from real or apparent distortion, and which are reasonably accurate" Various mechanical devices have heretofore been employed"but"these are rather complicated in their construction and have not proven wholly satisfactory in use. Various methods of' construction have also been employed which include locating a number of points on the ellipse to be drawn, and then connectingthe points with curved lines to give an approximation of the desired ellipse. The construction of an ellipse in this manner takes considerable time and is not always satisfactory in shape or appearance.

In accordance with the present inventionya ior construcdrawingimplement is provided which is simple "in itsconstruction, may be readily used by un skilled persons, and with which the desired approximate ellipse can be quickly drawn. Y

In accordance with the present invention; also, a drawing implement is provided with which reasonably accurate ellipses may be readily drawn. In accordance with the present invention; also,

a drawing implement is provided with whichapproximate ellipses of the desired size can be dravnI .7 Z.

Other advantageous features of the invention will be apparent from the annexed specification and claims. v

The nature andcharacteristic features ofthe "invention will be more readily understood from the following description, taken-in connection drawing implemena-in accordance with the 'pres- 'ent'invention; I

Fig. 3 is a diagrammatic view showing the manner of using the drawing implementin accordance with the present invention;

Fig. 4 is an edge view of the implement shown'in Figs. 1 and 2; and a Fig. 5 is a diagrammatic view illustrating the shape and relationship of the various edges of the drsiwing'implement. w 1

-It should, f course, he. understood that the all- .in one quadrant; ofanother isometric ellipse of smaller size, and. theseaxes lines intersect at the point .22. The-semhminoraxisifl insofar as can description and" drawings herein are illustrative merely, and that various modifications and changes may be made in the-structure disclosed without departing from the'spirit'of the invention.

- 1 Referring more particularly to the drawings, in which .a preferred embodiment .of the drawing implement" inaccordance with the present invention is illustrated, the drawing implement preierablyconsists of a flat sheet of transparent material, and preferably of synthetic plastic, having a compound or composite elliptical edge .portion I ll. curved and shaped-as hereinafter pointed out, a, major axis locusor envelop edge ll shaped and; curved as hereinafter pointed out, and a center locus line .I 2 thereon of a particular shape,

as hereinafter'pointed out.

Referring moreuparticularly to Fig. of the drawings, in whichthe shape: of the drawingimplement and.the mannner of constructing the :same are. illustrated in detail, the line,l5 represents thersemi-minor axis-and the line I6 represents the semi-major axis, both in one quadrant, of an ellipse, theaxis lines l5 and I6 intersecting at a' :center 'pointll.

The-axis lines l5 and i6 terminate at the ellipse at-the point Is and at the point is respectively. The portionof the curved edge Hllying between the point 19 and theipoint 18 is a truegquarter segment of an ellipse and in the embodiment shown the axis 1 lines audit, and the curve'lll are drawn for an isometricelli-pse in which the angle, of inxclination of the'object ,is' of the order of 16 -minutes..* i

The invention'is not,,however, limited to these specific ellipses but is adapted for approximate ellipses representing Jprojected'views of circles at other angles. p ,l

The line-2B and the line2l represent the semim'ajc'rand the semi-minor axes respectively, both be-seen' withthe eye and within drawing toler ancesterminates cnithe ellipse l9 to- I8 at the point 23 and for completing the quadrant of -this latter ellipse-,- .an elliptical extension is required below-and; beyond the. point-l9 to the terminus fll of the semi-major axis 2|. It has .-beenfound. that within drawing tolerances and 'lnsofarlas. can be ,seen with the eye the curve 23 to1=2 i, coincides,inqthe portion of its length from-23 to IBwith;the,.elliptical curve i8 190- I9. Thesemi-major. and semi-minor axes; 25 and 26, both .intheisame-rguadrant oienflhendsmaetrl of difierent sizes, another edge portion positioned with respect to said first edge portion and shaped to indicate the envelope of the major axes of the approximate isometric ellipses to be drawn, a locus line on said sheet between said edge portions adapted to indicate the intersection of the major and minor axes of the approximate isometric ellipses to be drawn, and gage markings on said sheet for determining the size of the approximate isometric ellipse to be drawn.

7. An implement for drawing approximate isometric ellipses of different sizes comprising a flat sheet of transparent material having a smooth continuous curved edge consisting of a composite of quarter segments of said ellipses to be drawn and adapted, when the implement is placed in various positions, for drawing quarter segments of approximate isometric ellipses of different sizes, another edge portion positioned with respect to said first edge portion and shaped to indicate the envelope of the major axes of the approximate isometric ellipses to be drawn, a locus line adapted to indicate the intersection of the major and minor axes of the approximate ellipses to be drawn, and gage markings on said first edge portion for determining the size of the approximate ellipse to be drawn.

8. An implement for drawing approximate ellipses representing circles of different sizes as projected from the same angle comprising a flat sheet of transparent material having a smooth continuous curved edge portion consisting of a composite of quarter segments of said ellipses adapted, when the implement is placed in various positions, for drawing selected quarter seg-- ments of said approximate ellipses, another edge portion spaced therefrom, a locus line between said edge portions corresponding in curvature to said curved edge portion and upon which the intersection of the major and minor axes of the approximate ellipses to be drawn is adapted to be disposed, and gage lines extending inwardly from said curved edge portion and normal thereto for determining the size of the approximate ellipse to be drawn.

ments of said approximate ellipses, another portion having thereon a locus line corresponding in curvature to said curved edge portion and upon which the intersection of the major and minor axes of the approximate ellipses to be drawn is adapted to be disposed, and gage lines interposed between said curved edge portion and said locus line and normal to said curved edge portion for determining the size of the approximate ellipse to be drawn.

JACK A. FULTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date D. 138,016 Gilardi June 6, 1944 866,152 Merritt Sept. 17, 1907 1,294,935 Milliken Feb. 18, 1919 2,075,854 Karnes Apr. 6, 1937 2,245,915 Hartrampf June 17, 1941 2,247,362 Dibble July 1, 1941 FOREIGN PATENTS Number Country Date 358,902 Germany Sept. 19, 1922 OTHER REFERENCES Pages 139 and 142 of catalogue entitled Drafting and Reproduction Materials and Equipment Slide Rules, 39th edition, copyright 1943, published by Keuffel and Esser Co., 127 Fulton Street, New York, N. Y. (Copy in Design Division, U. S. Patent Oflice.) 

